Computers are used in many applications. As computing systems continue to evolve, the graphical display requirements of the systems become more demanding. This is especially true in applications where detailed graphical displays must be updated quickly. One example of such an application is a computer game where movement and modification of background images may place great demands on the processing power of the computing system.
In order to display some screen images detailed textures are stored in memory. These textures are then molded and adapted to overlay or map to structures for display. An example is a brick pattern that is mapped to a wall structure, where if the wall is extending into the distance, the texture will be mapped in such a way to show perspective.
Often these textures are modified in ways to further enhance their utility. An example would be the blending of two separate textures to form a new texture. Another example includes modifying the lighting of the texture so as to simulate light coming from a singular source or from multiple sources. In some cases, a single texture may be modified by a number of operations in order to generate a new texture for use.
Multiple modifications to a texture are typically performed using a number of texture blend units. Each of the texture blend units would receive the texture or the product of a previous blend unit and combine it with another input to produce the desired output. The multiple blending units are cascaded to allow a number of different special effects to be applied to a single texture. In order to allow adequate modification of textures, many cascaded blend units may need to be included in the system. Large numbers of blend units add extra circuitry to the system that increases die area, testing requirements, and overall system complexity. All of these factors result in increased costs.
Therefore a need exists for a method and apparatus that allows for texture modification and blend operations to be performed in a simplified manner that utilizes less circuitry.